Supporting Information Liposome-Gold Nanorod/siRNA Complexes as a Potential Theranostic Agent using Multispectral Optoacoustic Tomography

Materials. DOTAP (1,2-dioleoyloxypropyl)-N,N,N-trimethylammonium chloride), DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and cholesterol (Chol) were purchased from Avanti Polar lipids (USA). Solvents (chloroform and methanol) were obtained from Fisher Scientific (UK). Scrambled siRNA and apoptotic siPLK1 were purchased from Eurogentec (Southampton, UK). The fluorescence dye NIR-797 (λexc=795nm, λem=817nm) was supplied by Sigma Aldrich and used conjugated with DOPE by adding NIR-797 (15mg, 0.017mmol) to a solution of DOPE (32mg, 0.042 mmol) and triethylamine (1mL) in chloroform. The mixture was stirred for two days and controlled by thin layer chromatography (TLC). Evaporation of the solvent was carried out and the resulting residue was purified on a silica column using step gradient elution. Commercially available gold nanorods (AuNR) with peak absorption in the near infrared (Ntracker 30-PM-700/780/850, Nanopartz Inc., Loveland, CO, USA) were employed to add optoacoustic contrast to the nanocarrier system. AuNR display high absorption in the NIR region and tunable longitudinal plasmon resonances dependent on their aspect ratio, and are thus highly suitable as optoacoustic contrast agents.[1, 2]